At present, thin film transistor liquid crystal display (TFT-LCD) devices, as main flat display devices in the prior art, have become important display devices in modern IT and video products. Liquid crystal display devices are widely used in various electronic products. During manufacturing of the liquid crystal display devices, there is an important technology, i.e., gate driver on array (GOA) technology. The GOA technology refers to manufacturing a row scanning drive signal circuit of a gate drive circuit on an array substrate of a liquid crystal display panel so as to realize a row by row scanning drive mode of the gate drive circuit. The gate drive circuit integrated on the array substrate by means of the GOA technology is termed a GOA gate drive circuit or a GOA circuit.
An existing GOA circuit generally comprises multiple GOA units in cascade connection. Each stage of GOA unit drives a corresponding stage of horizontal gate line. A GOA unit mainly comprises a pull-up part, a pull-up control part, a transfer part, a key pull-down part, and a pull-down holding part, and a boost capacitor which is configured to boost an electric potential.
The pull-up part is mainly configured to convert a clock signal into a gate signal. The pull-up control part is configured to control turn-on time of the pull-up part, and is generally connected with a transfer signal or a gate signal transmitted from a previous-stage GOA unit. The key pull-down part is configured to pull down a gate signal to a low electric potential as soon as possible, i.e., turn off the gate signal. The pull-down holding part is configured to hold a gate output signal and a gate signal of the pull-up part in a turn-off state (i.e., a negative electric potential). Generally, two pull-down holding parts are provided, and they function alternately. The boost capacitor is configured to boost a voltage at node Q for a second time, which is beneficial for outputting a G(N) signal of the pull-up part.
FIG. 1 schematically shows a GOA circuit in the prior art. An Nth-stage GOA unit charges an Nth horizontal gate line G(N) in an active area. The Nth-stage GOA unit comprises a pull-up control part 100, a pull-up part 200, a transfer part 300, a key pull-down part 500, a boost capacitor 400, a first pull-down holding part 600 and a second pull-down holding part 700.
The pull-up control part 100 comprises a thin film transistor T11. A gate of the thin film transistor T11 receives a transfer signal ST(N−1) from an (N−1)th-stage GOA unit; a drain thereof is connected to an (N−1)th horizontal gate line G(N−1); and a source thereof is connected to a gate signal node Q(N). The pull-up part 200 comprises a thin film transistor T21. A gate of the thin film transistor T21 is connected to the gate signal node Q(N); a drain thereof receives a clock signal CK; and a source thereof is connected to the Nth horizontal gate line G(N). The transfer part 300 comprises a thin film transistor T22. A gate of the thin film transistor T22 is connected to the gate signal node Q(N); a drain thereof receives a clock signal CK; and a source thereof outputs a transfer signal ST(N). The key pull-down part 500 comprises a thin film transistor T31. A gate of the thin film transistor T31 is connected to an (N+1)th horizontal gate line G(N+1); a drain thereof is connected to the Nth horizontal gate line G(N); and a source thereof is connected to a direct-current low voltage VSS. The key pull-down part 500 further comprises a thin film transistor T41. A gate of the thin film transistor T41 is connected to the (N+1)th horizontal gate line G(N+1); a drain thereof is connected to the gate signal node Q(N); and a source thereof is connected to the direct-current low voltage VSS.
Pull-down holding parts comprises two pull-down holding parts which are symmetrical to each other, i.e., the first pull-down holding part 600 and the second pull-down holding part 700.
During operation, a frequency of a first clock signal LC1 and a frequency of a second clock signal LC2 are lower than that of the clock signal CK input to the pull-up part 200, and a first circuit node P(N) and a second circuit node K(N) are enabled to have a high electric potential alternately, so that the two pull-down holding parts can operate in turns, thereby alleviating unfavorable effects caused when thin film transistors thereof are in a direct-current stress state for a long time.
For a large-size liquid crystal panel, since an RC loading thereof is relatively large, design of double-side drive is generally used, and a structure of the double-side drive is schematically shown in FIG. 2. A GOA circuit is provided on both sides of an active area, and gate driving signals are input to gate lines from both sides thereof. A double-side GOA drive circuit with an existing design is shown in FIG. 1, and each GOA circuit unit thereof comprises two pull-down holding parts.
A “narrow-bezel” television refers to a television having no obvious bezel covering a display panel of a display device thereof, so that the television has a simple and fashionable appearance. The “narrow-bezel” television has become a development trend of liquid crystal televisions by virtue of its simple and fashionable appearance.
However, the design of double-side drive of the GOA circuit unit having two pull-down holding parts cannot meet requirements for design of a narrow-bezel display panel because the GOA circuit unit has a large-size structure. Therefore, on the premise of meeting GOA drive requirements, an urgent problem to be solved is how to reduce a structure size of the GOA circuit unit as much as possible.